Chair base



July 2, 1968 w. H. SULLIVAN CHAIR BASE Filed Jan. 4, 1966 INVENTOR14/14/41 swan/4A4 B P A ATTORNEY$ United States Patent 3,390,421 CHAIRBASE William H. Sullivan, Shaker Heights, Ohio, assignor to The B. L.Marble Furniture, Inc, Bedford, 01:10, a corporation of Ohio Filed (Ian.4, 1966, Ser. No. 518,710 12 Claims. (Cl. 16-30) ABSTRACT OF THEDISCLOSURE A caster assembly for a chair base of the type havingoutwardly extending legs. The caster assembly includes a scuff platepositioned on top of the leg and a caster assembly positioned under thebottom of the leg. The scuff plate has a screw socket for receiving athreaded screw which is secured at its base to the chair caster andextends through the leg where it is threadedly engaged in the socket.The threaded connection permits opposed bearing surfaces on the scuffplate and on the caster assembly to be clamped rigidly against the chairleg.

This invention relates to chairs and more particularly to swivel chairbases.

Chairs of the typical office type have four legs extending outward fromthe center of the base. The seat is mounted on an upright post that isreceived in a socket in the center of the base, and the chair seatswivels relative to the base. Casters support the outer ends of the legsfor rolling the chair over the floor.

Usually, the chair casters have stems and sockets are drilled in thewood legs of the base for receiving the caster stems. The caster stemsare held in the sockets by friction. After the chair has been in use fora period of time, the lateral force exerted by the roller on the stemcauses the stem to enlarge the socket, so that the caster drops out.Another method of mounting a caster stem in a chair is to .drive thestem of the caster directly into the wood. In this type of mounting thestem is serrated to prevent turning relative to the leg and is glued inthe socket. Even this type of rigid mounting ultimately allows thecaster to work free and to drop out of the socket.

Another difficulty encountered with chair casters is that the stems ofthe casters may be bent during shipping. When this occurs, the socketbecomes enlarged and the caster drops out. Usually, the only remedy whenthe socket becomes enlarged is to replace the entire wood chair base,which is expensive. Attempts to fix a wood base having an enlargedcaster stem socket have been found to be generally unsatisfactory.

Accordingly, it is an object of this invention to provide an improvedwood chair base of the type having casters on the legs.

It is another object of this invention to provide a caster mounting fora wood chair base that securely maintains the caster stem in the base.

It is a further object of this invention to provide an improved woodchair base having a scuff plate and a caster securely mounted on eachleg.

These objects are accomplished in accordance with a preferred embodimentof the invention by a chair base in which the casters under each leg aresupported by a stem which extends through a hole in the leg. A scuffplate is applied to the top of each leg and each scuff plate has asocket that is aligned with the hole in the leg. The end of the casterstem is secured in the scuff plate socket and the stem does not turnrelative to the chair leg.

This preferred embodiment is illustrated in the accompanying drawings inwhich FIG. 1 is a perspective view of a chair base having the castermounting of this invention;

FIG. 2 is a side elevational view of one of the legs, partially in crosssection;

FIG. 3 is a cross sectional view of the leg along the line 3-3 in FIG.2; and

FIG. 4 is a cross sectional view of the leg along the line 4--4 in FIG.2.

As shown in FIG. 1, a chair base 2 has a center portion 4 which supportsan upright seat post (not shown). The base also includes outwardlyextending legs 6. Each of the legs is provided with a caster assembly 8.At the top of each leg 6 there is a scuff plate 10. The scuff plates .10are at the outer ends of the legs to protect the base from becomingmarred and to protect the shoes of the chairs occupant. Preferably, thescuff plates 10 are formed of a plastic material.

As shown in FIG. 2, the leg 6 has a recess 12 t0 accommodate the scuffplate, so that the upper surface of the plate is substantially inalignment with the top surface of the leg 6. The edges of the scuffplate adjacent the leg 6 have recessed shoulders 14 and 16. The scuffplate 10 has a rounded end portion and rounded longitudinal edges and isreinforced by a rib 18 which extends longitudinally through the scuffplate. A boss 20 is formed integrally in the scuff plate and projectsinto a socket 22 that is formed in the leg 6. A tubular insert 24 issecured in the boss 20 and has a flange 26 which abuts against thebottom of the socket 22. The insert 24 is secured in the boss 22 by arib 28 which engages a corresponding groove 30 in the insert 24.Preferably, the scuff plate 10 is molded around the insert 24, so thatthe insert is rigidly secured in the scuff plate. The frictionalengagement between the insert and the boss and between the flange 26 andthe socket 22 resists turning of the insert relative to the leg 6.

A bore 32 of a substantially smaller diameter than the socket 22 extendsthrough the leg 6 in alignment with the socket 22. A stem 34 on thecaster assembly 8 extends through the bore 32. The diameter of the bore32 is only slightly larger than that of the stem 34 so that the bore 32fits closely around the stem to resist bending of the stem. Externalthreads 36 on the stem 34 engage internal threads 38 in the insert 24.At the base of the stem 34 there is a circular plate 40 which fits inthe recess 42 in the leg 6. As shown in FIG. 2, the bottom of the recess42 extends substantially at right angles to the axis of the stem 34.Preferably, the plate 40 has radial grooves in its upper surface whichbite into the wood at the bottom of the recess 42 to resist turning ofthe plate relative to the leg 6.

The plate 40 forms the upper race of a ball bearing assembly 44. A wheel46 is mounted on a bracket 48 and the bracket 48 is journaled on thestem 34 for turning movement relative to the leg 6. The stem 34 extendsthrough the ball bearing assembly 44 and through the bracket 48. A head50 is formed on the end of the stem 34, preferably by cold working afterthe parts are assembled on the stem. Of course, any other suitablearrangement for mounting the bracket 48 on the stem 34 which permits thebracket 48 to turn relative to the stem could be substituted for theassembly shown in FIGS. 2 and 3.

The caster assembly of this invention is mounted in a chair leg 6 inwhich the recess 12, the socket 22, the bore 32 and the recess 42 havebeen formed. The caster assembly' 8 is preferably assembled as a unitarystructure with the bracket 48, and the ball bearing assembly 44 securedon the stem 34 by the head 50. The stem 34 is inserted through the bore32 until the plate 40 is positioned against the bottom of the recess 42,as shown in FIGS. 2 and 3. The scuff plate 10 is then assembled on theleg 6 by inserting the boss 20 into the socket 22 until the internalthreads 38 in the insert 24 engage the threads 36 on the end of the stem34. The plate 40 is then rotated relative to the scuff plate .10 untilthe stem 34 has been threaded into the insert 24 to such an extent thatthe scuff plate is rigidly secured in the recess 12 and the plate 40 ispressed tightly against the bottom of the recess 42. In this manner, thestem 34 is tightly secured in the leg 6.

The outer surface of the boss has a substantially larger diameter thanthe stem 34. Therefore, the boss otters resistance to transverse forcestending to enlarge the socket 22 and the bore 32. Accordingly, thecaster assembly 8 remains tightly affixed to the base 6 and provides along service life for the chair base.

If the caster assembly should become worn, or for some other reasonneeds to 'be replaced, the caster assembly can be removed from a chairleg 6, by unscrewing the stem 34 from the insert 24. Then, a new casterassembly may be installed in the leg 6.

While this invention has been illustrated and described in oneembodiment, it is recognized that variations and changes may be madetherein without departing from the invention as set forth in the claims.

I claim:

1. A caster assembly for a chair base having an outwardly extending legcomprising a scuff plate, a caster said scuif plate and said caster eachhaving opposed bearing surfaces, and means for securing together saidplate and said caster said securing means including means for adjustingthe distance between said opposed surfaces, whereby the scuff plate andthe caster may be clamped against opposite sides of said chair leg,

2. The caster assembly according to claim 1 wherein said securing meansincludes a stem extending between said caster and said scuff plate, saidsecuring means including screw thread means for adjusting the distancebetween said caster and said scuff plate.

3. The caster assembly for a chair base having an outwardly extendingleg comprising: a scuff plate on one side of said leg, a caster on theopposite side of said leg, and means for securing together said plateand said caster, said scuff plate having a boss projecting toward saidcaster and said securing mean including a stem on said caster, saidstern threadedly engaging said boss.

4. The caster assembly according to claim 1 wherein said caster has abearing plate in position to engage said leg and said securing meansincludes a stem fastened to said bearing plate.

5. The caster assembly for a chair base having an outwardly extendingleg comprising a scuff plate on one side of said leg, a caster on theopposite side of said leg, and means for securing together said plateand said caster, said caster having a bearing plate in position toengage said leg, said securing means including a stern fastened to saidbearing plate, said stem being threaded at the end opposite said bearingplate and said scuff plate being threadedly secured to said sternopposite end.

6. The caster assembly for a chair base having an outwardly extendingleg comprising: a scuff plate on one side of said leg, at caster on theopposite side of said leg, and means for securing together said plateand said caster, said scuff plate having a boss, said boss having athreaded socket therein, and said securing means including a stem onsaid caster, said stem having threads on the end opposite said caster,said stem threads engaging the threads in said socket.

7. The caster assembly according to claim 6 wherein said boss has aninsert therein, said insert including said socket and being metallic,and said boss being plastic.

8. The caster assembly according to claim 6 wherein said boss includesan insert, said insert including said socket and having a flangeextending across the end of said boss, and flange having a substantiallylarger diameter than said stem.

9. The caster assembly according to claim 3 wherein said scuff plate hasribs supporting said boss.

10. A caster mounting assembly comprising a chair leg having upper andlower sides, said leg sides being in opposed relation, a scuff plate atsaid upper side, a caster at lower side, said leg having a boreextending between said upper and lower sides, said caster having abearing surface engaging said lower side, said scutf plate having abearing surface engaging said upper side, a stem extending through saidbore, means securing one end of said stem to said caster and theopposite end to said scuff plate, said securing means including screwthreads for adjusting the distance between said scuff plate and saidcaster.

11. The caster mounting assembly according to claim 10 wherein said leghas a recess at said upper side, said recess and said scuff platecooperating to resist turning of said scuff. plate relative to said leg.

12. A caster mounting assembly according to claim 10 wherein said scuffplate has a boss aligned with said leg 'bore, said screw threads are onsaid stem opposite end and on said boss, whereby said stem and boss areadjustably secured together.

References Cited UNITED STATES PATENTS 2,217,754 10/1940 Johnson248-3451 2,292,445 8/1942 Hilldring 248-3451 2,587,886 3/1952 Penchoen248188.7 2,954,637 10/1960 Scherer 248-3451 2,992,803 7/1961 Good248188.7 3,148,855 9/1964 Hamilton 248-l88.7

BOBBY R. GAY, Primary Examiner. MARVIN A. CHAMPION, Examiner. D.TROUTMAN, Assistant Examiner.

